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| United States Patent |
6,086,647
|
|
Rahm
, et al.
|
July 11, 2000
|
Molasses/oil coal treatment fluid and method
Abstract
A composition and method for applying to a coal product for dust
suppression, water repellency, and spontaneous combustion potential
reduction. The composition includes molasses and a hydrocarbon-based
solution, such as an oil-containing solution. The oil-containing solution
is substantially free of water and may comprise about 20% asphalt. Both
the molasses and the oil-containing solution may comprise at least about
40% of the total composition by weight. The method of applying the
composition includes reducing a moisture content of a plurality of pieces
of coal, cooling the plurality of pieces of coal after said reducing step
and treating the plurality of pieces of coal after the reducing step, with
a composition comprising an oil and molasses.
| Inventors:
|
Rahm; Randall L. (Gillette, WY);
Avery; Kevin B. (Gillette, WY);
Berggren; Mark H. (Golden, CO)
|
| Assignee:
|
RAG Coal West, Inc. (Gillette, WY)
|
| Appl. No.:
|
235542 |
| Filed:
|
April 29, 1994 |
| Current U.S. Class: |
44/620; 44/572; 44/602; 252/88.1 |
| Intern'l Class: |
C10L 005/04; C10L 005/24 |
| Field of Search: |
44/620,602,572
252/88,88.1
|
References Cited
U.S. Patent Documents
| 1886633 | Nov., 1932 | Broeman | 44/545.
|
| 2098232 | Nov., 1937 | Fife | 44/602.
|
| 2222945 | Nov., 1940 | Groll et al. | 44/600.
|
| 3711318 | Jan., 1973 | Trechock et al. | 44/602.
|
| 3985516 | Oct., 1976 | Johnson et al. | 44/501.
|
| 3985517 | Oct., 1976 | Johnson | 44/501.
|
| 4201657 | May., 1980 | Anderson et al. | 208/23.
|
| 4265637 | May., 1981 | Anderson | 44/282.
|
| 4331445 | May., 1982 | Burns | 44/608.
|
| 4389218 | Jun., 1983 | Pike | 44/530.
|
| 4421520 | Dec., 1983 | Matthews | 44/501.
|
| 4501593 | Feb., 1985 | Paersch et al. | 44/564.
|
| 4582511 | Apr., 1986 | Siddoway et al. | 44/577.
|
| 4969928 | Nov., 1990 | Wen et al. | 44/568.
|
| 5310494 | May., 1994 | Bennett | 252/88.
|
Primary Examiner: Diamond; Alan
Attorney, Agent or Firm: Dahl, Esq.; Bruce E.
Dahl & Osterloth LLP
Claims
What is claimed is:
1. A method for producing a coal product from raw coal, comprising the
steps of:
heating the raw coal in a coal dryer;
reducing a moisture content of the raw coal using said heating step to
produce dried coal;
cooling the dried coal after said reducing step; and
treating the dried coal after said reducing step and all heating steps
involved in producing the coal product from the raw coal with a liquid
comprising oil and molasses to produce the coal product, wherein said oil
and molasses are mixed together before said treating step to provide said
liquid used by said treating step.
2. A method for producing a coal product as set forth in claim 1, wherein
said reducing step comprises reducing the moisture content of the raw coal
to less than about 10% by weight.
3. A method for producing a coal product as set forth in claim 1, wherein
said cooling step comprises cooling the dried coal to less than about
125.degree. F.
4. A method for producing a coal product as set forth in claim 1, further
comprising the step of:
heating the liquid to a temperature between about 50.degree. F. and about
250.degree. F. before said treating step.
5. A method for producing a coal product as set forth in claim 4, wherein
said step of heating the liquid increases the temperature of the liquid to
a temperature between about 150.degree. F. and about 170.degree. F.
6. A method for producing a coal product as set forth in claim 1, wherein
said treating step comprises forming a coating on the dried coal and
maintaining a substantially uniform concentration of the oil and molasses
throughout the coating.
7. A method for producing a coal product as set forth in claim 1, wherein
said treating step comprises spraying the liquid into the dried coal.
8. A method for producing a coal product as set forth in claim 1, wherein
said treating step comprises immersing the dried coal into the liquid.
9. A method for producing a coal product as set forth in claim 1, wherein
the liquid has a viscosity before said treating step, and wherein said
treating step comprises spraying the liquid, shearing the liquid during
said spraying step, and reducing the viscosity of the liquid by more than
about 25 percent during said shearing step.
10. A liquid for treating a coal product, comprising:
a mixture of molasses and a hydrocarbon-based solution, wherein:
said molasses is present in the amount of at least about 40% of said liquid
by weight; and
said hydrocarbon-based solution comprises a hydrocarbon portion wherein
said hydrocarbon portion comprises at least about 40% of said liquid by
weight, and wherein said molasses and said hydrocarbon-based solution are
mixed before being used in the treatment of the coal product.
11. A liquid for treating a coal product as set forth in 10, wherein said
hydrocarbon-based solution is substantially free of water.
12. A liquid for treating a coal product as set forth in 10, wherein said
hydrocarbon-based solution comprises asphalt.
13. A liquid for treating a coal product as set forth in claim 12, wherein
said asphalt makes up about 20% of said hydrocarbon-based solution by
weight.
14. A liquid for treating a coal product as set forth in 10, wherein said
hydrocarbon-based solution is substantially free of volatile fractions.
15. A liquid for treating a coal product as set forth in 10, wherein said
liquid has a viscosity of at least about 50,000 centipoise at 70.degree.
F.
16. A liquid for treating a coal product as set forth in claim 15, wherein
said liquid has a viscosity of less than about 3,000 centipoise at
150.degree. F.
17. A liquid for treating a coal product as set forth in claim 10, wherein
said liquid has a viscosity of at least 300,000 centipoise at about
700.degree. F.
18. A liquid for treating a coal product as set forth in claim 10, wherein
said molasses and said hydrocarbon-based solution each comprise about 50%
of said liquid on a weight percentage basis.
Description
FIELD OF THE INVENTION
The present invention generally relates to the processing of carbonaceous
materials. More particularly, the present invention relates to a
composition which can be applied to the surface of a carbonaceous
material, such as coal, to suppress the formation of dust, improve
moisture repellency, and/or reduce air flow therethrough to reduce the
potential for spontaneous combustion of the coal product during the
processing and/or storage thereof The present invention also relates to a
method for applying the composition to the carbonaceous material.
BACKGROUND OF THE INVENTION
In the processing of raw coal, it is generally considered beneficial to
reduce the moisture content of low-rank coals (e.g., lignite and
subbituminous coals) prior to shipment to the customer. Such reduced
moisture content upgrades the low-rank coal to enhance the coal product
heating value and decreases the weight of the coal to decrease
transportation costs.
Removal of surface moisture and interstitial moisture from low-rank coals
has the undesirable effect of increasing particle friability and dustiness
during handling. Some dustiness also occurs due to loss of surface
moisture by natural means during mining, preparation and storage. The
presence of dust is undesirable in that it impairs visibility, is harmful
if inhaled for long periods of time, and can result in loss of coal
product. More significantly, dustiness can also result in spontaneous
combustion during shipment and/or storage of the coal product.
Dust suppressants have been developed for reducing the dustiness of coals
and thereby reducing the incidence of spontaneous combustion. Some dust
suppressants are also designed to provide a relatively moisture repellant
coating on the coal product, thereby inhibiting moisture reabsorption into
the dry coal product which would reduce the product heating value. For
example, petroleum-based fluids have been applied to coal particles (i.e.,
sprayed or immersed) to reduce the dustiness of and provide a moisture
repellant coating to the coal product. However, petroleum-based fluids can
be expensive, typically have high sulfur content, and can have low
viscosities resulting in run-off. Molasses has also been utilized as a
dust suppressant. Molasses is readily available and is low in cost, but
lacks sufficient moisture repellency to be considered alone as a
high-grade coal dust suppressant.
Based upon the foregoing, there is a need for an improved dust suppressant
which can be economically applied to coal products to inhibit dust
formation and improve moisture repellency of the coal product. The
composition should have a high static viscosity at ambient temperature to
inhibit run-off of the composition during long-term storage of the coal
product. Further, the viscosity of the composition should substantially
decrease with increasing temperature and increasing shear rate to
facilitate application of the composition to the coal product.
SUMMARY OF THE INVENTION
The present invention achieves the above-stated requirements by providing a
novel method and composition for treating coal products.
The composition generally comprises molasses and a hydrocarbon-based
solution. In one embodiment, the molasses and the hydrocarbon portion of
the hydrocarbon-based solution each make up between about 40% and about
60% of the composition by weight. In another embodiment, the
hydrocarbon-based solution comprises an oil-containing solution which is
substantially free of water. The oil-containing solution may comprise
asphalt (e.g., up to about 50% of the solution by weight) to increase the
viscosity of the composition. The oil-containing solution may
advantageously be substantially free of volatile fractions so that
hydrocarbon gases are not emitted during handling, transportation, or
utilization. In order to inhibit run-off, the composition of the present
invention preferably has a viscosity of at least about 50,000 cp at
70.degree. F. In order to improve sprayability at elevated temperatures,
the composition of the present invention preferably has a viscosity of
less than about 3,000 cp at 150.degree. F. The composition of the present
invention may also exhibit significant shear thinning to facilitate
application thereof to the coal product by high-shear application methods,
such as spraying.
A method for applying the above-described composition is also disclosed.
The method generally comprises the steps of reducing the moisture content
of a plurality of pieces of coal by heating the same, cooling the
plurality of pieces of coal, and treating the plurality of pieces of coal
after the reducing step with a composition comprising molasses and an
oil-containing solution. The reducing step occurs before the cooling step
and preferably reduces the moisture content of the coal to less than about
10% by weight. The cooling step preferably reduces the temperature of the
coal to less than about 125.degree. F. The treating step may be performed
before or after the cooling step, but nonetheless is performed after the
reducing step. When treating the coal, the composition may be heated to at
least about 120.degree. F. to reduce the viscosity thereof and facilitate
application of the composition to the coal (e.g., by spraying). The
treating step advantageously may form a coating of the composition on the
coal and maintains a substantially uniform concentration of the molasses
and oil throughout the coating.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a chart illustrating the change in composition viscosity with
changing weight percent molasses.
FIG. 2 is a graph illustrating the effect of shear on the viscosity of
various compositions.
FIG. 3 is a graph illustrating the effect of temperature on the viscosity
of various compositions.
FIG. 4 is a block diagram of a general coal drying process in accordance
with principles of the present invention.
DETAILED DESCRIPTION
The present invention is based upon the properties and performance
characteristics of molasses and oil compositions applied to an upgraded
coal product for dust suppression, moisture repellency, and/or spontaneous
combustion potential reduction. It has been discovered that, when mixed in
the proper ratios, molasses and oil compositions exhibit particularly
desirable ambient viscosity, shear viscosity and high temperature
viscosity characteristics which provide enhanced dust suppression and
moisture repellency over the use of either molasses or oil alone, and
which provide enhanced application capabilities.
Typical properties of the individual components utilized for developing the
composition of the present invention are summarized in Table 1 below.
TABLE 1
______________________________________
Typical Properties of Molasses and Coal Treating Oil
Beet Molasses
Coal Treating Oil
______________________________________
Moisture, % 20-30 0
Sulfur, % 0.3-0.8 3-5
Viscosity at 70.degree. F., cp 2,000-30,000 5,000-25,000
Density, lb/gal 10-12 8-9
______________________________________
In the described embodiment, the molasses component comprises beet molasses
supplied by either the Holly Sugar Corporation or the Western Sugar
Company. The molasses generally comprises about 50 percent sugar, about 25
percent moisture, and about 25 percent proteins and dissolved salts. It
should be appreciated that the molasses component of the present invention
is not limited to beet molasses, and may instead include cane molasses or
other syrups or sugars. However, as will be discussed below, the use of
sugar alone in combination with oil has problems with separation.
The oil component of the present invention is a hydrocarbon-based solution.
Preferably, the oil exhibits little or no volatility at ambient
temperature so that hydrocarbon gases are not emitted during handling,
transportation or utilization. In the described embodiment, the oil
comprises a petroleum-derived coal treating oil supplied by Conoco, Inc.
(Product Code 1060). The Conoco oil comprises an aromatic hydrocarbon oil,
such as decant oil, mixed with about 20 percent asphalt material, such as
a 100 penetration asphalt obtained during conventional petroleum refining.
The Conoco oil is described in more detail in U.S. Pat. No. 4,201,657 to
Anderson et al., which is incorporated herein by reference. Other oils may
be used, including coal-derived, plant-derived, and animal-derived oils.
It has been discovered that blends of beet molasses and oil produce a thick
liquid which is of greater viscosity than either component individually.
FIG. 1 illustrates the effect of the molasses:oil ratio on composition
viscosity. Compositions containing between 40 percent and 60 percent
molasses and oil exhibit significantly greater viscosities than the
individual components alone. More specifically, such compositions have
viscosities well in excess of 100,000 cp at 70.degree. F., while the
individual components have maximum viscosities on the order of about
30,000 cp at 700.degree. F. Equal parts of the two components result in
substantially greater viscosity than other mixtures tested (i.e., on the
order of about 700,000 cp at 70.degree. F. for a 50:50 mixture of Western
molasses and Conoco coal treating oil containing 20 percent asphalt).
Without being limited to a particular theory, it is believed that the
unexpected extreme increase in viscosity may be due in part to
hydrogen-bonding interactions between the oil and molasses. It is this
increased viscosity of the molasses and oil compositions which constitutes
one of the desirable aspects of the present invention.
The Conoco oil and Holly and Western molasses components each individually
exhibit nearly Newtonian rheological behavior. This characteristic is
reflected in the observation that viscosity remains nearly constant as a
function of shear rate, as illustrated in FIG. 2. Blends of molasses and
oil containing greater than about 40 percent and less than about 60
percent molasses, however, exhibit significant shear thinning, or
pseudoplastic rheological behavior. This desirable characteristic leads to
relatively low viscosity (i.e., compared to the viscosity at low shear)
under the high shear conditions which are encountered in spray nozzles. As
a result, good atomization and coverage of the treatment composition onto
coal is possible. The characteristic of decreasing viscosity as a function
of increasing rotational speed of the viscometer spindle, as illustrated
in FIG. 2, is indicative of shear thinning.
The same shear-thinning behavior leads to relatively high viscosity at low
shear (i.e., when the treatment composition is at rest on the surface of
the coal). As a result, the treatment remains near the particle surfaces
after application and is available to capture additional dust which may be
generated during subsequent handling. In addition, the high viscosity at
low shear inhibits loss of treatment composition due to run-off during
storage. However, as can be seen in FIG. 2 and as noted above, the
viscosity of the composition of the present invention is significantly
reduced by the shear forces imparted thereon during spraying. In one
embodiment, the viscosity of the composition is reduced by at least 25
percent, and preferably by more than about 75 percent, during spraying by
the noted shear-thinning effect which facilitates the application of
compositions of the present invention onto the coal product.
The viscosities of molasses, oil, and blends of molasses and oil all
decrease with increasing temperature as illustrated in FIG. 3. However,
the rate of viscosity decrease with an increase in temperature is greater
for compositions in accordance with principles of the present invention.
This desirable feature allows the treatment composition of the present
invention to be heated and thereby thinned during spraying for improved
atomization and product coverage. FIG. 3 specifically illustrates an
example of viscosity decrease as a function of increasing temperature
exhibited by blends of Holly beet molasses and Conoco oil containing 20
percent asphalt. Viscosity decreased by roughly two orders of magnitude
when temperature increased from 70.degree. F. to 150.degree. F. for all
molasses:oil blend ratios tested For example, the 50:50 ratio sample
decreased in viscosity from about 300,000 cp at 70.degree. F. to about
2,000 cp at 150.degree. F. The optimum spraying temperature can be
resolved for any particular treatment application by experimentation.
However, in one embodiment, the temperature of the composition when
sprayed ranges from about 150.degree. F. to about 1700.degree. F.
Thickeners and additives may be added to increase viscosity of the
composition. For example, in the examples noted above, Conoco 85100
asphalt was added to the Conoco oil at a concentration of about 20 percent
prior to blending with molasses. The oil exhibited a viscosity increase of
about a factor of three as a result of the asphalt addition. Both the
Conoco oil and the Conoco oil with asphalt exhibit nearly Newtonian
rheological behavior (no shear thinning).
Similarly, sugar may be added to the oil to increase viscosity. In one
example, sugar was added to Conoco oils with and without asphalt at a
concentration of about 30 percent by weight. In each case, viscosity
increased by a factor of about two. Nearly Newtonian rheological behavior
was observed in each case after sugar addition. Other additives including,
but not limited to, waxes and polymers may be included to tailor viscosity
and tackiness to a particular application.
Surprisingly, the blending of molasses and oil results in a stable mixture
which exhibits the desirable property of little or no separation during
storage and handling. That is, the mixture is substantially homogeneous
and remains so even when on the coal product. Molasses blended with oil
across all ratios tested in the examples noted above exhibited no apparent
separation. By contrast, a mixture of sugar and water (1:1 ratio by
weight) was prepared and then blended with Conoco oil at a ratio of one
part sugar water to one part oil. The resulting mixture exhibited rapid
separation of the water and oil components. Additives including, but not
limited to, surfactants and emulsifiers may be added to optimize mixture
characteristics for particular types of syrups and oils. However, in the
case of the oil and molasses composition, no emulsifiers are needed for
mixing the oil and molasses into a substantially homogenous mixture.
As may be evident from the above description of the composition, the
preferred method of application of the composition to the coal product is
spraying. For example, the composition may be heated to between about
50.degree. F. and 250.degree. F. to decrease the viscosity of the
composition and sprayed through a known spray nozzle. As noted, in one
embodiment, the composition is heated to a temperature of about
150.degree. F. to about 170.degree. F. before spraying. However, it should
be appreciated that other methods of application may be utilized. For
example, the coal product may be immersed in a bath of the composition and
subsequently removed therefrom to provide composition coverage over the
surface of the coal product. Moreover the composition may be applied in a
blender such as the PK Zig-Zag.RTM. Continuous Blender by Patterson-Kelley
Co. of East Stroudsbury, Pa. Furthermore, the coal product may be treated
in coal transfer chutes or at the discharge of conveyors.
The effectiveness of a particular dust suppressant can be measured
utilizing an opacity meter. The opacity meter is based on the principle of
light transmittance through a cloud of dust created when approximately 200
grams of sample are dropped into a vertical cylinder chamber of
approximately 4 inches in diameter and 32 inches in length. A laser
provides a beam of light which is passed through the dust cloud to a photo
detector. Light transmittance at a period of time after dropping a test
sample into the chamber is used as a relative indicator of sample
dustiness. Samples may be tested as-produced and also after tumbling in an
apparatus and procedure as described in ASTM D-441, Friability Test for
Coal. Experience has shown that the tumbling procedure provides conditions
which a raw coal or upgraded coal product must endure in the laboratory
without significant dust production in order to be handled and transported
industrially.
Table 2 below shows results of laboratory tests performed to illustrate the
relative dustiness of raw coal ("as is" from the mine), upgraded (dried)
coal product, and upgraded (dried) coal product treated with a commercial
petroleum-based spray agent. The raw coal and products shown in Table 2
were produced at a nominal minus 3/4-inch particle size containing
significant fractions of fine material (less than 1/4 inch). The table
provides the moisture content of each freshly prepared coal or coal
product and the dustiness based on opacity reader meetings taken as
described above.
TABLE 2
______________________________________
Effect of Drying and Treatment on Subbituminous Coal Dustiness
Opacity Test Result, % Light
Transmittance, 15 Seconds After
Product
Dropping Sample.sup.a
% H.sub.2 O
As Produced
After Tumbling.sup.b
______________________________________
Raw Coal 30.8 100.0 100.0
Dry, Untreated Coal 9.4 82.9 26.7
Dry, Oiled Coat.sup.c 9.9 98.4 100.0
______________________________________
.sup.a 100% = No dust.
.sup.b Using ASTM D441 tumbler apparatus.
.sup.c Treated with 6 gallons Conoco coal treating oil per ton of product
As can be seen in Table 2, the raw coal sample exhibited no dustiness. Thi
is a result of the saturation of internal coal pores with moisture and the
presence of surface moisture, which acts to adhere coal fines. During
industrial-scale drying of a similar raw coal, total moisture was reduced
from approximately 30 percent to less than 10 percent. The untreated,
upgraded coal product exhibited significant dustiness, particularly
following the tumbling procedure described above. A similar upgraded coal
produced was treated with Conoco coal treating oil using an application
rate of six gallons per ton with the result that dustiness was nearly
eliminated.
Table 3 compares laboratory dustiness data using various potential
alternative dust suppressants. Industrially produced upgraded coal was
treated in the laboratory at a rate of six gallons treatment composition
per ton of product. These test results show that beet molasses alone did
not perform as well as Conoco oil alone for suppression of dust at a
comparable application rate. Slight dilution of the molasses resulted in a
significant improvement of results; however, performance was still
noticeably poorer than oil alone. A freshly prepared product treated with
a 1:1 oil:molasses mixture provided dustiness results which nearly matched
those of the oil alone.
TABLE 3
______________________________________
Effect of Treatment on Dry Subbituminous Coal Dustiness
(6 Gallons Per Ton Application Rate for Each Treatment)
Opacity Test Result, % Light
Transmittance, 15 Seconds After
Product
Dropping Sample.sup.a
Treatment Type
% H.sub.2 O
As Produced
After Tumbling.sup.b
______________________________________
Conoco Coal Treating Oil
9.9 98.4 100.0
Beet Molasses 9.9 95.2 83.7
10:1 Molasses:Water 10.0 97.1 97.6
1:1 Oil:Molasses 9.5 98.6 99.2
______________________________________
.sup.a 100% = No dust.
.sup.b Using ASTM D441 tumbler apparatus.
Table 4 below summarizes results obtained from coal and upgraded products
following treatment with oil, molasses, and a blend of oil and molasses on
an industrial scale. Results are shown for products as-produced and after
stockpiling. The coals shown in Table 4 were stockpiled for a few weeks
prior to sampling. The tests were conducted during different industrial
scale test operations. In general, stockpiling of coal or products results
in degradation due to moisture changes and oxidation. Temperatures
monitored in the stockpiles showed that all products exhibited some self
heating. Previous experience has shown that many untreated upgraded
products cannot be stockpiled without sealing surfaces to block airflow.
Untreated products will often produce heat from oxidation and will
eventually exhibit spontaneous combustion in locations where heat is
generated at a rate greater than it is dissipated. Treated products in
these examples exhibit heating but at a much lower rate due to physical
and chemical effects of product pore blockage by the treatments.
TABLE 4
______________________________________
Effect of Treatment Type and Stockpiling on Dry Coal Dustiness
As Produced After Stockpiling
Opacity Test Opacity Test
Result, % Light Result, % Light
Coal Transmittance, Transmittance, 15
and Treatment Product 15 Seconds After Product Seconds After
Type % H.sub.2 O Dropping.sup.b % H.sub.2 O Dropping.sup.b
______________________________________
Raw Coal,
29.5 99.9 23.8 21.6
Untreated
Dry, Oil 9.9 100.0 12.1 90.3
Treated
Dry, Treated -- -- 12.5 63.2
Molasses
Dry, Treated 10.8 100.0 5.3 97.1
Molasses/Oil
______________________________________
.sup.a All treated coals received an application of about 6 gallons per
ton.
.sup.b 100% = No dust.
The results in Table 4 show that the raw coal became very dusty after
stockpiling due to loss of moisture. Removal of surface moisture liberated
fines which had been adhering to the particle surfaces. The oil-treated
upgraded product also exhibited an increase in dustiness (i.e., light
transmittance decreased from 100.0 to 90.3 percent) during stockpiling
while exhibiting an increase in moisture content from 9.9 to 12.1 percent.
It is thought that oxidation of the product rather than moisture changes
are responsible for the increased dustiness of this product.
A similar product treated with molasses was not sampled as-produced for
dustiness testing but was initially produced at about 10 to 11 percent
moisture and contained very little dust based on visual observation. After
stockpiling, a significant dustiness was measured (i.e., light
transmittance value of 63.2 percent) even though moisture content
increased somewhat.
A similar upgraded product, which was treated with a blend of molasses and
oil, exhibited the smallest increase in dustiness of all coals or products
tested following stockpiling. Even though this product lost moisture
during stockpiling (i.e., decreased from 10.8 to 5.3 percent), dustiness
showed only a slight drop from the as-produced value.
A treatment application rate of 6 gallons per ton was selected for the
series of tests described above. Depending on the particular nature of the
coal or product, the application rate can be adjusted to provide the
desired degree of dust control. An additional consideration in the overall
application rate is the oil addition requirement to impart moisture
repellency to the product. For example, moisture repellency can be induced
in molasses and oil mixtures at an oil concentration lower than that
required to induce favorable shear-thinning flow properties. In some
applications, treatments containing low concentrations of oil will perform
satisfactorily and may constitute an optimum formulation.
The general methodology of producing a coal product in accordance with
principles of the present invention is schematically illustrated in FIG.
4. Generally, a stream of raw coal (e.g., having a moisture content of
about 30% by weight) is provided from a source 10 (e.g., a crusher or
grinder) to a dryer 20 (e.g., a fluidized bed reactor). In the dryer 20,
the moisture content of the raw coal therein is reduced to the desired
degree (e.g., by passing a heated gas through the bed of coal).
Thereafter, coal is removed from the dryer 20 and directed to a cooler 30
(e.g., another fluidized bed reactor) where the temperature of the "dried"
coal is reduced to the desire degree (e.g., 125.degree. F. and by, for
instance, passing ambient temperature air through the coal in the cooler
30). After the desired temperature is achieved, the coal may be directed
to a treatment fluid applicator 40 which applies a composition in
accordance with principles of the present thereto to the coal. However, as
noted above this composition may be applied in a variety of manners.
Moreover, it should be noted that although the composition is illustrated
as being applied after exiting the cooler 30, broadly the present
invention includes applying the composition at any time after "drying" the
coal to the desired degree. A more detailed discussion of a coal drying
process is disclosed in U.S. Pat. No. 4,354,825 to Fisher et al., the
entire disclosure of which is incorporated by reference herein.
The foregoing description of the present invention has been presented for
purposes of illustration and description. Furthermore, the description is
not intended to limit the invention to the form disclosed herein.
Consequently, variations and modifications commensurate with the above
teachings, and the skill or knowledge of the relevant art, are within the
scope of the present invention. The embodiments described hereinabove are
further intended to explain best modes known for practicing the invention
and to enable others skilled in the art to utilize the invention in such,
or other, embodiments and with various modifications required by the
particular applications or uses of the present invention. It is intended
that the appended claims be construed to include alternative embodiments
to the extent permitted by the prior art.
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